000
AXPZ20 KNHC 241604
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON AUG 24 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...SPECIAL FEATURE...

A BROAD AREA OF LOW PRESSURE IS CENTERED ABOUT 550 NM SW OF THE 
SRN TIP OF BAJA CALIFORNIA NEAR 16N116W. THE FIRST VISIBLE 
SATELLITE IMAGES OF THE DAY SHOW AN EXPANSIVE AREA OF DEEP 
CONVECTION IN THE WRN SEMICIRCLE...WHICH HAS ALSO GAINED 
CURVATURE OVER THE PAST SIX HOURS. HOWEVER...MODERATE ELY SHEAR 
CONTINUES TO IMPACT THE SYSTEM AND IS LIMITING CONVECTIVE 
ORGANIZATION E OF THE CENTER. A HIGH RESOLUTION QUIKSCAT PASS AT 
1304 UTC REVEALED 25 TO 30 KT WINDS OVER THE E SEMICIRCLE OF THE 
SYSTEM INDICATING THE SYSTEM IS ON THE VERGE OF BECOMING A 
TROPICAL DEPRESSION. THERE IS A HIGH CHANCE...GREATER THAN 50 
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE 
NEXT 48 HOURS...MORE LIKELY SOONER. 
  
...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 07N78W TO 07N95W TO 
16N113W TO 11N130W TO 13N140W. SCATTERED MODERATE FROM 05N TO 
08N BETWEEN 78W AND 83W. SCATTERED MODERATE FROM 04N TO 07N 
BETWEEN 94W AND 98W. SCATTERED MODERATE TO ISOLATED STRONG FROM 
13N TO 16N BETWEEN 105W AND 108W. SCATTERED MODERATE TO ISOLATED 
STRONG WITHIN 120 NM OF THE AXIS BETWEEN 120W AND 137W.  

...DISCUSSION...

N OF 20N...
THE MID-UPPER PATTERN HAS BECOME MORE ZONAL OVER THE PAST 24 
HOURS WITH A RIDGE/TROUGH/RIDGE PATTERN EVIDENT ACROSS THE 
REGION. THE RIDGE EXTENDS FROM AN ANTICYCLONE NEAR 21N144W NE 
THROUGH 23N135W TO 32N130W. DOWNSTREAM TROUGH EXTENDS FROM A 
CYCLONIC CIRCULATION OVER NW ARIZONA ACROSS NORTHERN BAJA 
CALIFORNIA TO A BASE NEAR 21N127W. A VAST AREA OF DRY AIR ALOFT 
IS ASSOCIATED WITH THESE FEATURES...RESULTING IN GENERALLY FAIR 
WEATHER CONDITIONS. A NARROW RIDGE AXIS EXTENDS FROM THE 
INTERMOUNTAIN REGION OF THE U.S. ACROSS W MEXICO TO ANOTHER 
UPPER LEVEL HIGH JUST OFF THE SOUTHERN TIP OF BAJA CALIFORNIA 
NEAR 22N113W. 
AT THE SURFACE...HIGH PRES IS CENTERED N OF THE AREA NEAR 
36N137W. NE 15-20 KT TRADES EXIST ACROSS THE NW CORNER AND N 
15-20 KT WINDS NEAR THE N BAJA COAST WITH GENERALLY LIGHTER 
WINDS IN BETWEEN. A MIX OF N AND S SWELL WILL MAINTAIN SEAS OF 6 
TO 8 FT ACROSS MUCH OF THE AREA THROUGH MID-WEEK.

S OF 20N...
A DEEP MOIST ENVIRONMENT IS PRESENT ACROSS MUCH OF THE 
TROPICS...ENHANCED BY DIFFLUENT MID-UPPER FLOW TO THE S OF THE 
ANTICYCLONE NEAR 22N113W. THE DIFFLUENT FLOW IS ENHANCING 
CONVECTION ASSOCIATED WITH THE LOW PRESSURE AREA NEAR 16N116W
BUT ALSO PROVIDING EASTERLY SHEAR OVER THE SYSTEM AS WELL. SEE 
SPECIAL FEATURES SECTION FOR ADDITIONAL DETAILS. LONG 
PERIOD...14-16 SECOND...S TO SW SWELL IS PROPAGATING ACROSS MUCH 
OF THE AREA AND WILL CONTINUE FOR ANOTHER DAY OR SO BEFORE 
SUBSIDING.

$$
COBB